From: Stephen Warren <swarren@xxxxxxxxxx> Modify cmd_dtc to run the C pre-processor on the input .dts file before passing it to dtc for final compilation. This allows the use of #define and #include within the .dts file. Signed-off-by: Stephen Warren <swarren@xxxxxxxxxx> --- v5: * Update Documentation/kbuild for the new command and rule. v4: * Use -x assembler-with-cpp so pre-defined macros are set up so that #included header files know to only use cpp syntax, not C syntax. * Define __DTS__ for similar reasons. * use $(CPP) not $(CC) -E, and use $(cpp_flags). * Save the pre-processed results so they can be easily inspected when debugging build issues. * The use of -x assembler-with-cpp causes cpp to recognize directives in column 1 only. Hence, there's no need to escape property names that begin with #. Hence, there's no need for separate skeleton.dtsi and skeleton.dtsip. Maintain a separate file extension and build rule so that CPP-usage is opt-in. In particular, when using CPP, #include must be used rather than /include/ so that dependencies work. v3: Pass "-x c" not "-xc" to cpp. v2: Place make %.dtb: %.dtsp rule into Makefile.lib. --- Documentation/kbuild/makefiles.txt | 23 +++++++++++++++++++++++ scripts/Makefile.lib | 9 +++++++++ 2 files changed, 32 insertions(+), 0 deletions(-) diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt index a0b0671..dfe6838 100644 --- a/Documentation/kbuild/makefiles.txt +++ b/Documentation/kbuild/makefiles.txt @@ -1194,6 +1194,29 @@ When kbuild executes, the following steps are followed (roughly): clean-files += ... *.dtb + dtc_cpp + This is just like dtc as describe above, except that the C pre- + processor is invoked upon the .dtsp file before compiling the result + with dtc. + + In order for build dependencies to work, all files compiled using + dtc_cpp must use the C pre-processor's #include functionality and not + dtc's /include/ functionality. + + Using the C pre-processor allows use of #define to create named + constants. In turn, the #defines will typically appear in a header + file, which may be shared with regular C code. Since the dtc language + represents a data structure rather than code in C syntax, similar + restrictions are placed on a header file included by a device tree + file as for a header file included by an assembly language file. + In particular, the C pre-processor is passed -x assembler-with-cpp, + which sets macro __ASSEMBLY__. __DTS__ is also set. These allow header + files to restrict their content to that compatible with device tree + source. + + A central rule exists to create $(obj)/%.dtb from $(src)/dts/%.dtsp; + architecture Makefiles do no need to explicitly write out that rule. + --- 6.8 Custom kbuild commands When kbuild is executing with KBUILD_VERBOSE=0, then only a shorthand diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib index 425578e..33432f4 100644 --- a/scripts/Makefile.lib +++ b/scripts/Makefile.lib @@ -269,6 +269,15 @@ cmd_dtc = $(objtree)/scripts/dtc/dtc -O dtb -o $@ -b 0 $(DTC_FLAGS) -d $(depfile $(obj)/%.dtb: $(src)/dts/%.dts FORCE $(call if_changed_dep,dtc) +dtc-tmp = $(subst $(comma),_,$(dot-target).dts) + +quiet_cmd_dtc_cpp = DTC+CPP $@ +cmd_dtc_cpp = $(CPP) $(cpp_flags) -D__DTS__ -x assembler-with-cpp -o $(dtc-tmp) $< ; \ + $(objtree)/scripts/dtc/dtc -O dtb -o $@ -b 0 $(DTC_FLAGS) $(dtc-tmp) + +$(obj)/%.dtb: $(src)/dts/%.dtsp FORCE + $(call if_changed_dep,dtc_cpp) + # Bzip2 # --------------------------------------------------------------------------- -- 1.7.0.4 -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
